/*
 * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
 * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 * 
 * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
 * 
 * 
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 * 
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address: 
 * 
 * 	Pearson Education, Inc.
 * 	Rights and Contracts Department
 * 	75 Arlington Street, Suite 300
 * 	Boston, MA 02216
 * 	Fax: (617) 848-7047
*/ 

#include <iostream>
using std::cout;
using std::endl;

// calculate val!, which is 1 * 2 * 3 ... * val 
int factorial(int val) 
{
    if (val > 1)
        return factorial(val-1) * val;
    return 1;
}

bool is_pos(int i)
{
	return i > 0 ? true : false;
}

// calculate val!, which is val * val - 1 * val - 2 ... * val - (val - 1) * 1
int fact(int val)
{
	int ret = 1; // local variable to hold result as we calculate it

	while (val > 1) {
		ret *= val;  
		--val;
	}

	return ret;            // return result
}

int main()
{
	cout << factorial(5) << endl;
	cout << fact(5) << endl;
	cout << factorial(0) << endl;
	cout << fact(0) << endl;
	return 0;
}

